Method of making non-planar fibrous articles



E. A. MORSE Feb. 2S, 96?

METHOD OF MAKING NON-PLANAR FIBROUS ARTlCLES 4 Sheets-Sheet l I OriginalFiled Sept. 13, 1952 Feb. 28, 1967 I E. A. MORSE 3,396,795

METHOD OF MAKING NON-PLANAR FIBROUS ARTICLES Original Filed Sept. 13,1962 I 4 Sheets-Sheet 2 i i L 1,64

Feb. 28, 1967 E. A. MoRsE 3,305,795

METHOD OF MAKlNG NON-PLANAR FIBROUS ARTICLES Original Filed Sept. 13,1962 4 SheetS-Sheet 3 Feb. 28, 1967 E. A. MORSE 3,306,795

METHOD OF MAKING NON-PLANAR FIBROUS ARTICLES Original Filed Sept. 13,1962 4 SheetS-Sheet 4 ATTORNEY nited States Patent l fifice l3,306,795Patented Feb.. 2s, 1967 3,306,795 METHOD F MAKEN@ NON-PLANAR FEBRGUSARTICLES Edward A. Morse, Fanwood, NJ., assigner to Johnson & .lohusorna corporation of New Jersey Original application Sept. 13, 1962, Ser.No. 223,488, pow Patent No. 3,262,451, dated `luly 26, 1966. Divided andthis application Nov. 12, 1965, Ser. No. 507,503 8 Claims. (Cl. 156-85)This application is a division of my copending application Serial No.223,488, filed September 13, 1962, now U.S. Patent No. 3,262,451, issuedJuly 26, 1966.

This invention relates to preformed articles and methods of making themand more particularly to preformed non-planar articles containing one ormore relatively thick layers of fibrous material for absorbing orpadding purposes.

Many different types of articles -containing relatively thick layers offibrous material are used on the body for surgical purposes, forabsorbent purposes, as padding, and the like. Examples of such articlesare absorbent dressings, which are used for absorbing the exudate ofwounds, sanitary napkins, which are used to absorb menstrual fluid, andlactation pads, which are used to absorb lacteal fluid. In the making ofcasts for setting broken bones, a fibrous padding is often placedbetween portions of the cast and the part of the body being placed inthe cast.

Usually, such articles are made in a flat or planar form. However, inorder to function properly, the articles should be held in intimatecontact with the body. In most instances, the configurations of theparticular parts of the body against which they are placed in use arenot fiat. Therefore, in order for the articles to be held in intimatecontact with such body parts, they must be distorted from their originalplanar configurations which are non-planar. For example, sanitarynapkins are customari-ly made in a fiat, rectangular shape. However, theconfiguration of the vaginal area against which they are placed in useis arcuate. Therefore, the napkins must be distorted from their flatshape into one which approximates the arcuate conguration of the vaginalarea. Lactation pads for absorbing lacteal fluid, usually originallyflat, are distorted in use into a generally hemispherical shape toconform them to the chest contours.

Distorting of such originally planar articles into shapes which arenon-planar often results in discomfort and in an impairment of theirfunction, particularly if they are used for absorbent purposes. Thesearticles are customarily made from one or more layers of fibrousmaterials usually enclosed within a woven or non-woven fabric cover.When distorted, the layers are folded and creased. These folds andcreases may not only cause discomfort, but may also effect the absorbingeffectiveness of the article. It would be desirable, therefore, toprovide such articles in a preformed shape to eliminate the necessityfor distortion.

I have discovered that preformed, non-planar articles of the foregoingtype may be simply and economically provided through the use ofshrinkable, orientated plastic materials in the form of lms, filaments,bands, yarns, webs and the like. The articles may be made by securing toa surface of one or more relatively thick layers of fibrous material,such as a bat of absorbent wood pulp fibers or cotton of the typecommonly used for absorbing and padding purposes, a layer of anaxiallyorientated plastic material of the foregoing type, e.g., a film,sheet, strands, filaments, subjecting the laminate so formed toconditions which cause the oriented plastic material to shrink whereuponthe material assumes dimensions smaller than its original dimensionsand, in so doing, causes the fibrous layer to which it is secured toassume a non-planar shape. Articles of differ-ent shapes may beobtained, as desired, by appropriate selection of the materials used andby appropriate selection of the treating processes. They may be madeeconomically at high speeds on relatively inexpensive equipment.

The plastic materials which may be employed in the articles of myinvention, and in the methods of making them, include axially-orientedfilms, sheets, threads, filaments, strands and the like of polystyrene,polyvinyl chloride, polypropylene, polyethylene and methyl methacrylate.Such axially-oriented materials are yobtained by stretching standardplastic materials, after they are formed by conventional solutioncasting or extruding techniques, to a larger size in one or moredirections, usually accompanied by the application o-f heat to one orboth surfaces of the material, whereupon the material becomes thinnerand the molecules comprising the material are rearranged from agenerally random arrangement into one which is of a more orderlypattern. Materials o-f this type are available in the form of films fromvario-us sources, as for example from the Plax Corporation under thenames Polyflex and Methaflex; from the Cordite Company under the nameCordite 1,000; from W. R. Grace & Company under the name Cryovac; andfrom Goodyear Tire and Rubber Company under the name Vitafilm ST. Thesefilms may be slit into strands or bands of different widths.

By way of illus'ratin-g the invention, vI shall refer more specificallyto axially-oriented films of plastic materials. It is to be understood,however, that axially-oriented plastic materials in forms other thanfilms may be used in various embodiments of the invention.

Most axially-oriented films currently available are biaxially oriented.A biaxially-oriented film is one which has been stretched bothlongitudinally and transversely, Le., stretched in two mutuallyperpendicular directions. The degree of biaxial orientation may be thesame in both directions, or it may be different. As a result of ltheaxial o-rientation, certain forces are built up into the films,providing, in effect, what might be termed as elastic memory. Theseforces can be released and the films shrunk from their stretched,axially-oriented sizes to smaller sizes by exposing them to heat. I mayutilize this feature of such films in the practice of my invention'.

Axially-oriented plastic films can be obtained With varying shrinkcharacteristic-s. For example, W. R. Grace & Companys S Film, 'a vinylchloride-vinylidene chloride copolymer, shrinks .about 45% at 205 F.;their D Fi-lm, an irradiated, medium dens-ity polyethylene, shrinksabout 50% at 250 F., and their Y Film, a polyproplyene, shrinks aboul55% -at 310 F. Films which may be shrunk up to of their preshrunk,axially-oriented size are available. The shrink characteristics of thefil-ms at different temperatures may also vafry. By selectivelyutilizing these properties of the films, the types of non-planararticles which may be made in accordance with this invention may bevaried as desired. In addition, oriented plastic films can be providedto have controlled 'amounts of shrinking in one or more directions,i.e., machine direction and transversely thereof, with equal ordifferent degrees of shrinkage in the different directions. Thesecharacteristics also lend themselves to the preparation of preformed,non-planar articles which are shaped in one or more dimensions, and indifferent ways.

Upon orientation, the films gain in tensile strength. Further, filmswhich are waterproof or which are soluble in water are available. Thesefeatures may be suitably employed in the making of various embodimentsof the invention.

A preformed, arculately shaped sanitary napkin which is curved in thedirection of its lengt-h is -a preferred embodiment of an articleincorporating the invention. A

napkin of this form has the general arcuate configuration of the vaginalarea against which it is positioned in use and thus is comfortable towear, less conspicuous and absorbs fluid more eiciently.

In accordance with this invention, such a preformed, arcuately shapedsanitary napkin may be made by adhesively bonding an axially-orientedplastic film to a surface of one or more relatively thick, flat layersor bats of absorbent 4fibrous 4material which fonm components of asanitary napkin, and then subjecting the composite so formed to heatwhich causes the film to shrink. When the axially-oriented film shrinks,it causes the layer or layers of absorbent brous materi-al to which itis bonded to assume a non-planar configuration, e.g., to curve. In otherforms of the invention, different portions of the axiallyorientedplastic film may be selectively shrunk, while other parts remainunshrunk or relatively unshrunk.

In the drawings:

FIG. l is a diagrammatic view of apparatus for making an a-rcuatelyshaped body, such .as a curved sanitary napkin, in accordance with theinvention;

FIGS. l(a) through 1U) and 2 illustrate the sequential steps in themaking of the napkin on the apparatus of FIG. l;

(FIG. l(fz) is a fragmentary perspective view of a wood pulp board priorto comminuting to form a continuous fibrous bat from which pads whichconstitute absorbent components of the napkin are cut;

FIG. l(b) covered on the top, sides and bottom longitinuous absorbentfibrous bat formed from the wood pulp board of FIG. l(a);

FIG. l(c) is .a transverse sectional view of the bat of FIG. 1(b)covered on the top, sides and bottom longitudinal edge poritons with anaxially-oriented plastic film;

FIG. 2 is a nenlarged view of FIG. 1(c);

FIG. l(d) is a fragmentary side elevational view of a series ofabsorbent pads cut from the bat of FIG. 1(17) and l(c) disposed inspaced relationship and enclosed within a continuous length of coveringfabric, such as a non-Woven fabric;

FIG. l(e) is a view of individual napkins prior to being a-rcuatelyshaped formed by cutting the cover of the covered pads of FIG. lfd)between spaced pads to provide attachment tabs which are folded aroundthe pads;

FIG. 1(1) is a side elevational view of an arcuately shaped napkinprepared from the napkin of FIG. l(e) and incorporating the invention;

FIG. 3 is another form of the invention illustrating in longitudinalsection yan axially-oriented sheet of plastic film secured to arelatively thick layer of fibrous material and illustrating by thearrows the direction of application of heat to the composite so formed;

FIG. 4 is a view of the composite of FIG. 3 after shrinking theaxially-oriented plastic film by heat to cause the composite to assume anon-planar configuration, eg., a

curve;

FIG. 5 is a view, in longitudinal section, of another embodiment of theinvention which includes an axiallyoriented sheet positioned between andsecured to relatively thick layers of absorbent fibrous material ofdifferent types and also illustrates by arrows the direction ofapplication of heat;

FIG. 6 is a view of the composite of FIG. 5 illustrating theconfiguration assu-med by the composite after the film is shrunk;

FIG. 7 is a top plan view of a disc-shaped laminate of anaxially-oriented plastic film secured to a similarly shaped disc ofabsorbent material prior to formation into a hemispherically shaped pad;

FIG. 8 is a sectional view of the disc-shaped laminate of FIG. 7 takenalong a diameter and further illustrating by the arrows the direction ofapplication of heat thereto;

FIG. 9 is a top plan view, partly cut away, of the laminate of FIG. 8after heating and shrinking the filing FIG. 10 is la side elevationalview, partly cut away, of FIG. 9 illustrating its hemispherical shape;

FIG. ll is a diagrammatic view of a modified form of the apparatus ofFIG. l;

FIG. l2 is a side elevational view of preforminrg inolds used inconnection with the apparatus of FIG. l1 and holding a napkin;

FIG. 13 is a right side view of FIG. l2;

FIG. 14 .is -a side elevational view of an arcuately shaped napkin madeon the apparatus of FIG. ll; and

FIG. l5 is a perspective view of an arcuately shaped napkinincorporating the invention, partly cut away to reveal its innerconstruction, and wit-h its attachment tabs extended.

A typical sanitary napkin incorporating the invention is illustrated inFIG. l5. The napkin it) includes an elongated absorbent pad l2 in theform of a layer of comminuted wood pulp libers 2 inches wide, 8 incheslong, L inch thick and weighing about l5() grains having a selectivelyshrunken, axially-oriented plastic film 14 of polyvinyl chloride,three-quarters of a mil thick, coextensive with and adhesively bonded tothe bottom I6, sides 18, and top longitudinal edge portions Ztl of thepad. The composite Vso formed is enclosed within a wrapper of fabric 22,such as a non-woven fabric, which extends beyond the ends of the pad toprovide the usual attachment tabs 24. The napkin is arcuately shaped inthe direction of its length with the plasic film positioned on theoutside of curvature so that when the napkin is placed against the bodywhen worn, the film will be on the side of the napkin away from thebody. The lm, because of its water-proof properties, acts as a iiuidbarrier and prevent menstrual iiuid absorbed by the pad of wood pulpfibers from striking through. the bottom of the napkin.

A napkin of the foregoing type may be made in accordance with thefollowing method on the apparatus illustrated in FIG. l. Bleachedsulfite wood pulp board 26 is fed from a supply roll 28 into acomminuting mill 30 which disintegrates the board to form individualizedwood pulp fibers. The bers are laid down in the form of a continuousbulky, absorbent bat 32 of the type illustrated in FIG. l(b), on anendless belt movingrhorizontally below the mill. The bat isapproximately two inches wide, three-quarters of an inch thick, and hasa density of about grains per eight inch length. An axially-orientedpolyvinyl chloride film 34, three-quarters of a mil thick and fourinches wide, such as the type available from the Goodyear Tire andRubber Company under the designation Vitafilm ST, is fed from a supplyroll 36 positioned above the endless belt on which the Continous bat ofwood pulp fibers is moving below, past a roll type adhesive applicator3S which applies a light coating of adhesive, such as Rhoplex HA-S, soldby Rohm & I-Iass Corporation, to one surface of the film. The film maybe shrunk about 40% in the direction of its length and is essentiallynon-shrinkable in the direction of its width by exposure to hot air at250 C. for 6 seconds. A film which is biaxially-oriented may also beused.

Directly after being coated with the adhesive, and while the adhesive isstill wet, the lm 34 is positioned on top of the continuous bat 32 ofwood pulp fibers with the adhesive coated side of the film in contactwith the bat to which it becomes bonded. The film is positioned to coverthe top surface 4@ and both sides 42 of the bat by folding devices whichalso lightly compress the bat somewhat to reduce its dimensions.Preferably, the film also extends inwardly over the longitudinal sideedge portions :t4 of the bottom of the bat for a short distance, e.g.,one-quarter of an inch.

The bat with the oriented plastic film adhesively bonded to it thenproceeds to a cutting device 46 which severs the bat and the film intothe individual film-covered pads 12 approximately eight inches long.After cutting, the individual pads are positioned in spaced relationshipon top of a horizontally moving, continuous length of a non-woven fabric48 fed from a supply roll 50 and which is of sufficient width, eg., 61/2inches wide, to be folded around the spaced film-covered pads with thelongitudinal edges of the non-woven fabric disposed in overlappingrelationship on the top of the pads. The overlapped edges of thenon-woven fabric are thus disposed on the same side of the pad as theaxially-oriented polyvinyl chloride film. This is the side which, in thefinished napkin, is placed away from the body. If desired, theoverlapped longitudinal edges of the non-woven fabric may be sealed byan adhesive applied as a line by means of an applicator 52.

The spaced pads enclosed within the non-woven fabric cover next pass toa cutting and stacking device 54 wherein the portions 56 of non-wovenfabric cover extending between adjacent ends of adjacent pads are cutapproximately midway between the pad ends, thus forming flat sanitarynapkins of the conventional type having an absorbent core and an outercover the ends of which extend beyond the ends of the core to form theattachment tabs 24. In the cutting and stacking device, the attachmenttabs are also folded around against the face of the'pads covered withthe film and the pads then rearranged from a` spaced horizontal positionto a vertical position with adjacent pads in contact with each other.

The pads so disposed are next directed into a forming oven 53 throughwhich they move continuously. Hot air at a temperature of about 250 C.is applied through jets to both sides 18 of the vertically aligned padsfor a period of about six seconds as they move through the oven to heatthe film covering the sides. The application of the hot air in thislocalized manner causes the portion of the filmpeovering the sides ofthe pad, i.e., the portion upon which 'the hot air impinges, to shrink.In shrinking, the pad is caused to assume a curved configuration toprovide a napkin of the shape illustrated in FIGS. IU) and l5. Thenapkins are then permitted to cool.

By localizing the application of the heat to the film covering the sidesof the pads as they move through the oven, shrinkage of the film occursprimarily in those portions. Some shrinking'may also occur in thoseportions of the film which cover the longitudinal top and bottom edgesof the pad. Most of the portion of the film extending across the bottomsurface of the pad remains unshrunken or shrunken to a lesserextent thanthose portions covering the sides of the pad. By maintaining the pads inintimate, face-to-face contact with respect to each other as they passthrough the forming oven, the faces of the pads are insulated byadjacent pads, thereby minimizing the exposure of those surfaces to theapplied heat. By so directing the application of the heat to the film,while insulating or partially insulating other portions of the film,selective shrinkage of the film and selective curvature of the resultingarticle may be obtained.

In FIGS. 3 and 4 there is illustrated another curved articleincorporating the invention which includes a relatively thick,rectangular shaped layer 60 of fibrous material, such as a plurality ofsuperposed layers of cotton cords, having an axially-oriented plasticfilm 62 secured toit. The arrows in FIG. 3 illustrate that the heat isapplied to the film side of the laminate so formed. Upon the applicationof heat, the film shrinks and in so doing causes the layer of cotton tocurve with the film on the inside of curvature, as illustrated in FIG.4. Articles so formed .may be used as padding for casts. If desired,curvature in 'such articles may be obtained either lengthwise of thelayer of fibrous material, or transversely thereof, or in bothdirections. If an article curved in only one direction is desired, afilm oriented essentially or predominately in one direction is used.

In FIGS. 5 and 6 there is illustrated a further embodiment of theinvention which includes two layers of fibrous material, one of which isless resistant to being curved than the other. For example, the toplayer 64 may be a relatively thick layer of comminuted wood pulp fibersand the bottom layer 68 a layer of cotton fibers of equal thickness. Thelayer of wood pulp fibers is less resistant to being curved than thelayer of cotton fibers. A biaxiallyoriented plastic film 70 is placedbetween the layers and is bonded to both layers. When the film is heatedby the application of heat in the direction of the arrows as illustratedin FIG. 5, the film shrinks, thus curving both layers of fibers. Thearticle is curved with the layer of wood pulp fibers on the inside ofcurvature since it is less resistant to being curved, and with the layerof cotton on the outside of curvature. l

A still further embodiment of the invention is illustrated in FIGS.7-10. This embodiment is illustrative of the formation of ahemispherically shaped article in accordance with the invention. Adisc-shaped layer 72 of fibrous material has a like shaped,multi-axially-oriented film 74 adhesively bonded to one surface. Amulti-axially-oriented film is one which has been stretched in aplurality of directions extending radially -outwardly from the center ofthe film. Heat is applied to the peripheral portions 76 of the film sideof the laminate so formed in the locations designated by the crosses inFIG. 7 and in the direction indicated by the arrows in FIG. 8, while thecentral portion of the film is insulated. Applying heat to theperipheral portions of the film causes the film in those portions toshrink to provide a hemispherically shaped article of the typeillustrated in FIGS. 9 and 10. Articles of this shape may be used aslactation pads and for similar purposes.

Any suitable means may be used to cause shrinkage of the film. Hot airis preferred, although hot water and steam may be suitably employed.Alternatively, instead of applying heat t-o cause shrinkage of theaxially-oriented film during the manufacturing operation, the articlecontaining the axially-oriented film may be stored at elevatedtemperatures which causes shrinking of the film to take place over asomewhat more extended period of time. The amount and rate of shrinkagewhich occurs is generally related to the time and temperature; greaterand more rapid shrinking is obtained when high temperatures are used.

Instead of using films of axially-oriented plastic films whosedimensions are generally the same as the dimensions of the surface orsurfaces of the layers of fibrous material to which they are secured,one Ior more strips of such films may be applied to such surfaces ofsuch layers in different patterns. By way of example, a preformed,arcuately shaped absorbent fibrous body suitable for use as a sanitarynapkin and similar to the embodiment described above but not having amoisture barrier may be provided by applying strips of axially-orientedplastic film only to the sides and longitudinal edge portions of oneface of the absorbent fibrous pad, with the other surfaces thereof beingfree from such lm. Shrinking the strips of plastic film will cause theabsorbent fibrous pad to which they are bonded to assume a `curvedconfiguration. In another form, a plurality of parallel, aligned strandsof axially-oriented plastic material suitably positioned on and bondedto a surface of the fibrous material may be used.

The extent to which the film shrinks is governed by factors such as thetemperature of the heating medium which causes shrinkage, the time theheat is applied and upon the particular axially-oriented film used. Apredetermined degree of shrinkage may be obtained in one or moredirections with greater or lesser amounts of shrinkage obtained byapplying the heat at different temperatures, and for different periodsof time, to different p0rtions of the axi-ally-oriented plastic film. Byproper selection of the particular axially-oriented film used and byproper control of the application of the heat causing shrinkage of thefilms, articles of various non-planar configurations may be obtained.

The curvature assumed by the absorbent fibrous layer to which theaxially-oriented plastic film is bonded is determined by the resistanceto curving of the fibrous llayer as well as by the amount of shrinkagewhich can be obtained in the plastic film. A relatively thin layer of anabsorbent fibrous material which does not greatly resist being curved,such as a layer of wood pulp fibers, will be curved more easily than asimilarly sized layer of cotton fibers because cotton fibers tend toresist deformation more than wood pulp tibers. Greater or lesser amountsof curvature in each of the foregoing types of absorbent fibrous bodiesmay thus be obtained by approximately selecting the particular fibrousmaterial used.

ln addition, the ability of the film to cause a layer of fibrousmaterial to curve is influenced by the shrink tension of the film. Theterm shrink tension is a measurement of the amount of force anaxially-oriented lrn exerts while it shrinks. If, because of theparticular absorbent fibrous material used, or because of the amountused, a relatively great amount of force is required to cause thefibrous material to curve, a film having a high shrink tension may beused. On the other hand, if a lesser amount of force is required, a filmhaving a low shrink tension may be used.

if it is desired to use a film which has a low shrink tension to make anarticle having components which would ordinarily require a film having ahigh shrink tension to cause curvature, the article may first bepreformed into essentially its desired form and the film then shrunk.Preforming the article before shrinking the film reduces the resistanceto curving and consequently the amount of force the film is required toexert to cause curvature and to hold the article in its curved form.

Such articles may be made by methods and on apparatus similar to theabove-described method and apparatus for making an arcuately shapedsanitary napkin by using preforming molds. Apparatus which uses suchmolds is illustrated in FIGS. ll-l2. The apparatus is identical with theapparatus illustrated in FG. l up to and including the adhesiveapplicator 52 for applying a line of adhesive to the overlappedlongitudinal edges of the cover to seal the edges. Directly after theadhesive is applied to the overlapped longitudinal edges of the cover,and just before the covered, spaced pads enter into the cutter andstacker, they pass through a turnover device 78 which inverts the coverand the pads to a position with the film side of the pads down. Theportions of the cover between the pads are then cut in the cutter andstacker to form sanitary napkins of conventional liat form as describedabove.

As the sanitary napkins pass from the cutter and stacker, they areplaced into molds Sl) which preform the napkins into the general shapedesired and hold the napkins in such shape in their passage through theforming oven wherein the film is shrunk.

As illustrated in FIGS. l2 and 13, a typical preforming mold for use inmaking an arcuately shaped napkin incorporating the invention maycomprise a pair of spaced, arcuately shaped metal plates 82, 82 whichdefine an .arcuately shaped napkin receiving pocket which isapproximately of the configuration desired in the finished napkin. For anapkin having a pad eight inches long, :the mold may have a radius ofcurvature of four inches yon the inside of the mold. The molds areslightly narrower than the width of the napkin so that the longitudinaledges of the napkin extend beyond the edges of the mold.

A series of such molds are supported in spaced reationvship on twospaced, parallel endless chains Sli which pass horizontally through andbelow the oven 58 in continuous cyclical movement. The chainsaresupported on and moved by sprockets 86 driven by any suitable means,

lEach mold is supported on the chains by means of lrnetalsupport.members88 one end 90 of each of which hold thegarcuately shaped metal platesforming the preforming mold and the other endv v92 of each of which issecured toa collar 94 keyed to a horizontal axle or shaft 94 whichextends beyond the collar and beyond the chains.

CII

The shaft is rotatably connected to each chain by a bushing k6 securedto the chain and positioned on the shaft on each side of the collar.Thrust collars 10i) are provided on the shaft outside of the bushings.The ends of the shaft beyond the thrust collars are provided withbearings 162 which ride in tracks which follow the pattern of the chainsand which define the movement of the molds in their cyclical movementthrough the oven. One end 104 of the shaft is provided with a trailinglink 106 secured at its forward end to the shaft and at its rearward endWith a bearing 108 which rides in a cam track to maintain the mold in anupright position in its passage through the oven.

Such molds are located in spaced relationship on the chains which intheir movement drive the molds through the oven in continuous timedrelationship. The molds are spaced from each other on the chains asufiicient distance to receive a sanitary napkin as it is dischargedfrom the cutter and stacker and with clearance between adjacent moldsholding napkins.

As a napkin is discharged from the cutter and stacker, it is positionedin a mold which is moving in the direction of the oven. The tab ends ofthe napkin cover are positioned behind the surface of the napkinadjacent to the face 110 of the mold by any suitable mechanism. Thenapkin is placed in the mold with the side of the pad covered with theaxially-oriented plastic film adjacent to the face of the mold. Locatingthe napkin in this manner is achieved by inverting the covered padsprior to their entry into the cutter and stacker as disclosed above.

A napkin discharged from the cutter and stacker is of conventional fiatform and hence must be forced into the arcuately shaped mold in order tobe preformed. This may be accomplished by means of side restrainingslides 112 which urge the napkin into the mold. As illustrated in FIG.11, the side restraining slides may be in the form of curved metal barslocated on each side of the molds just as they enter into the cutter andstacker to receive a discharged napkin. The side restraining slides arespaced apart a distance slightly smaller than the width of the napkinand thus define an opening smaller than the napkin width through whichthe napkins pass on their way to the forming oven. As the napkins passthrough the opening, the inner surfaces of the slides engage the outeredges of the napkin at approximately the central portion of the lengthof the napkin and exert a drag or restraining action on the napkin. Suchaction causes the napkin, which is straight, to be urged back into themold and to general conformity with it.

As the napkin moves toward the oven, the top and bottom ends of thenapkin contact a set of top and bottom restraining slides 114 and 116,respectively, which may be in the form of angle irons. These restrainingslides are positioned in superposed relationship and extend horizontallythrough the oven above and below the napkin. The distance between theinner faces of the slides is slightly less than the height of the napkinwhen it is in the mold. These top and bottom restraining slides begin toexert their restraining action just before the napkins enter the oven.Since the napkins have been induced to assume the configuration of themold by the side restraining slides, as soon as the top and bottomrestraining slides contact the top and bottom ends of the napkins, thenapkin will be held within the mold and the side restraining slides areno longer necessary and may terminate. The napkins are thus held in themold in a preformed configuration as the molds and the napkins held bythem pass through the oven.

As the napkins pass through the oven, jets of hot air are applied to theside edges of the napkins in the manner described above causing the filmcovering the sides to shrink. The portions of the film extending acrossthe' bottom surfaces of the pads are adjacent to the molds and are thusinsulated by the molds. Since the opposite faces of the napkins areexposed, the portions of the film extending along the front surface ofthe pads are also exposed and thus will also shrink, thereby assistingin curving the napkins.

In a continuous operation, the molds pass through the oven withregularity and may become heated and their insulating propertiesdecreased. As a result, the portion of the film extending across theback of the pad may also become heated and may shrink. It is desirable,therefore, to cool the molds after they leave and before they enter theoven for another cycle by any appropriate means, such as by cooling airnozzles 118.

By using such preforming molds, oriented plastic films having lowershrink tension may be employed since in the preforming operation, theresistance of the pad of fibers to curving which the film must overcometo induce such curving is substantially reduced. After the film hasshrunk, the napkins, upon their removal from the mold and cooling,maintain their arcuate configuration. Obviously, molds may also be usedto preform an article in these operations where films having high shrinktensions are used.

It is apparent that modifications, variations and changes may be made inthe foregoing illustrative embodiments of the invention while stillremaining within its spirit.

What is claimed is:

1. The method of making a preformed, non-planar fibrous body comprisingsecuring a heat shrinkable, axiallyoriented layer of plastic to asurface of a relatively thick layer of fibrous material with thedirection of axial orientation of said plastic layer being in thedirection that said fibrous body is to be made non-planar, and heatingsaid plastic layer while so secured to said fibrous layer to shrink saidplastic layer and thereby form and hold said fibrous layer in anon-planar configuration.

2. The method in accordance with claim 1 wherein said layer of plasticis a film.

3. The method of making a preformed, non-planar fibrous body comprisingheating a relatively thick layer of fibrous material having a heatshrinkable, axially-oriented plastic layer secured to a surface thereofwith the direction of axial orientation of said plastic layer being inthe direction that said fibrous body is to be made nonplanar wherebysaid plastic layer shrinks to form and hold said fibrous layer in. anon-planar configuration.

4. The method of making a preformed, non-planar fibrous body comprisingsecuring a heat shrinkable, axially-oriented layer of plastic to asurface of a relatively thick layer of fibrous material with thedirection of axial orientation of said plastic layer being in thedirection that said fibrous body is to be made non-planar, forming saidfibrous layer and plastic layer assembly into a shape approximating thenon-planar shape desired, and then heating said plastic layer while sosecured to said fibrous layer to shrink said plastic layer and therebyhold said fibrous layer in the non-planar shape desired.

5. The method in accordance with claim 1 wherein said layer of plasticis multi-axially oriented.

6. The method in accordance with claim 1 wherein portions .of said layerof plastic are heated to a greater extent than other portions to shrinkselectively said plastic layer.

7. The method of making an arcuately shaped sanitary napkin comprisingsecuring a heat shrinkable, axially-oriented layer of plastic to asurface of a relatively thick elongated layer of fibrous material, thedirection of axial orientation of said layer of plastic being in thedirection of the length of said fibrous layer, enclosing said layerswithin a cover, and heating said plastic layer in the direction of saidlength while so secured to said fibrous layer to shrink said plasticlayer and thereby form and hold said sanitary napkin in an arcuateshape.

8. The method in accordance with claim 7 wherein said fibrous layer andplastic layer assembly is preformed into approximately the shape desiredbefore said plastic layer is heated.

References Cited by the Examiner UNITED STATES PATENTS 2,304,989 12/1942 Snowden 264-342 2,784,456 3 1957 Grabenstein. 2,964,040 12/ 1960Ashton et al. 128-290 3,092,246 6/ 1963 Harrison et al. 264-3423,178,495 4/ 1965 Richard et al 264-288 X EARL M. BERGERT, PrimaryExaminer.

l?. DIER,y Assistant Examiner.

1. THE METHOD OF MAKING A PREFORMED, NON-PLANAR FIBROUS BODY COMPRISINGSECURING A HEAT SHRINKABLE, AXIALLYORIENTED LAYER OF PLASTIC TO ASURFACE OF A RELATIVELY THICK LAYER OF FIBROUS MATERIAL WITH THEDIRECTION OF AXIAL ORIENTATION OF SAID PLASTIC LAYER BEING IN THEDIRECTION THAT SAID FIBROUS BODY IS TO BE MADE NON-PLANAR, AND HEATING